Symptoms of P0628
- Check-engine light, sometimes with several unrelated codes at once.
- Warning lights, a no-start, or intermittent electrical faults.
- Communication or module-reset problems on a scan tool.
Common causes of P0628
- Low battery voltage, poor grounds, corroded connectors, or blown fuses.
- Wiring or network (CAN bus) faults between modules.
- A module software/programming issue, or rarely a failed controller.
Useful checks before replacing parts
- Check pump command, relay or module output voltage, pump current, fuel pressure, ground voltage drop, freeze-frame data, and companion fuel pump codes.
- Inspect for short-to-ground faults, open power feeds, corroded pump connectors, weak grounds, damaged tank harness wiring, and failed pump module outputs.
- Load-test the circuit while commanding the pump to locate voltage drop or missing current.
Related OBD-II codes
These nearby computer entries can help compare wording and pin down the fault area.